mail/wrapper/mail-wrapper

   1 #!/usr/bin/env bash
   2 #
   3 # mail-wrapper -- Report results of a command by email
   4 # Copyright (c)2017,2018,2023 Alexander Barton (alex@barton.de)
   5 #
   6 # This program is free software; you can redistribute it and/or modify
   7 # it under the terms of the GNU General Public License as published by
   8 # the Free Software Foundation; either version 2 of the License, or
   9 # (at your option) any later version.
  10 #
  11
  12 NAME=$(basename "$0")
  13
  14 # Include "ax-common.sh":
  15 ax_common_sourced=
  16 for dir in "$HOME/lib" "$HOME/.ax" /usr/local /opt/ax /usr; do
  17         [ -z "$ax_common_sourced" ] || break
  18         ax_common="${dir}/lib/ax/ax-common.sh"
  19         # shellcheck source=/usr/local/lib/ax/ax-common.sh
  20         [ -r "$ax_common" ] && . "$ax_common"
  21 done
  22 if [ -z "$ax_common_sourced" ]; then
  23         echo "Error ($NAME): \"ax-common.sh\" not found, aborting!" >&2
  24         echo "Please install 'ax-unix', \"Alex' UNIX Tools & Scripts\", and try again."
  25         exit 99
  26 fi
  27 unset dir ax_common ax_common_sourced
  28
  29 usage() {
  30         {
  31                 echo
  32                 echo "Usage:"
  33                 echo "  $NAME [--help|--usage]"
  34                 echo "  $NAME {parameters} [<command> [<arg> [<…>]]]"
  35                 echo
  36                 echo "  -C                      Use the \"C\" locale, no localized (error) messages."
  37                 echo "  --dontfail|-n           Don't return the error code of the command called."
  38                 echo "  --errors|-e             Generate email on errors only."
  39                 echo "  --from|-f               Email address of the sender of the email."
  40                 echo "  --stderr-is-warning|-W  Exit code indicates error; stderr is only warning."
  41                 echo "  --subject|-s <subject>  Subject for the email."
  42                 echo "  --time|-t               Include timing information."
  43                 echo "  --to|-t <address>       Email address to send the email to."
  44                 echo
  45                 echo "When no <command> is given, $NAME reads from standard input. The default for"
  46                 echo "<from> and <to> for the current user is \"$to\"."
  47                 echo
  48         } >&2
  49         exit "${1:-0}"
  50 }
  51
  52 syntax_error() {
  53         ax_error -l "Syntax error!"
  54         usage 2
  55 }
  56
  57 clean_up() {
  58         if [[ -z "$proc_fd_works" ]]; then
  59                 ax_debug "Cleaning temporary files ..."
  60                 [[ -n "$buffer_file" ]] && rm -f "$buffer_file"
  61                 [[ -n "$error_file" ]] && rm -f "$error_file"
  62         fi
  63 }
  64
  65 # Convert UNIX time stamp to date text.
  66 time_t_to_date() {
  67         t="$1"
  68         shift
  69         if ! date -d @"$t" "$@" 2>/dev/null; then
  70                 # "date -d @<time_t>" (GNU variant) failed!
  71                 date -r "$t" "$@"
  72         fi
  73 }
  74
  75 time_t_to_duration() {
  76         s="$1"
  77         if [[ "$s" -ge 60 ]]; then
  78                 m=$((s / 60))
  79                 s=$((s % 60))
  80                 if [[ "$m" -ge 60 ]]; then
  81                         h=$((m / 60))
  82                         m=$((m % 60))
  83                         if [[ "$h" -ge 24 ]]; then
  84                                 d=$((h / 24))
  85                                 h=$((h % 24))
  86                                 echo "${d}d${2}${h}h${2}${m}m${2}${s}s"
  87                         else
  88                                 echo "${h}h${2}${m}m${2}${s}s"
  89                         fi
  90                 else
  91                         echo "${m}m${2}${s}s"
  92                 fi
  93         else
  94                 echo "${s}s"
  95         fi
  96 }
  97
  98 case "$(uname)" in
  99         "Darwin")
 100                 unset proc_fd_works
 101                 ;;
 102         *)
 103                 proc_fd_works=1
 104 esac
 105
 106 # Initialize internal state.
 107 buffer_file=""
 108 error_file=""
 109 error_level=0
 110 host=$(hostname -f 2>/dev/null || hostname)
 111
 112 trap clean_up EXIT
 113
 114 # Some defaults (can be adjusted by command line parameters).
 115 unset do_errors_only
 116 unset dont_fail
 117 unset stderr_is_warning
 118 unset subject
 119 unset time
 120 from="${LOGNAME:-root} <${LOGNAME:-root}@$host>"
 121 to="$from"
 122
 123 # Parse the command line ...
 124 while [[ $# -gt 0 ]]; do
 125         case "$1" in
 126                 "-C")
 127                         unset LANG
 128                         export LC_ALL="C"
 129                         ;;
 130                 "--debug"|"-D")
 131                         export DEBUG=1
 132                         ;;
 133                 "--dontfail"|"-n")
 134                         dont_fail=1
 135                         ;;
 136                 "--errors"|"-e")
 137                         do_errors_only=1
 138                         ;;
 139                 "--from"|"-f")
 140                         shift
 141                         [[ $# -gt 0 ]] || syntax_error
 142                         from="$1"
 143                         ;;
 144                 "--help"|"--usage")
 145                         usage
 146                         ;;
 147                 "--subject"|"-s")
 148                         shift
 149                         [[ $# -gt 0 ]] || syntax_error
 150                         subject="$1"
 151                         ;;
 152                 "--stderr-is-warning"|"-W")
 153                         stderr_is_warning=1
 154                         ;;
 155                 "--time"|"-t")
 156                         time=1
 157                         ;;
 158                 "--suppress-empty")
 159                         # Ignore this switch for compatibility with an other
 160                         # "mail-wrapper" script. This is the default anyway!
 161                         ;;
 162                 "--to"|"-t")
 163                         shift
 164                         [[ $# -gt 0 ]] || syntax_error
 165                         to="$1"
 166                         ;;
 167                 "-"*)
 168                         syntax_error
 169                         ;;
 170                 *)
 171                         # Command to execute follows in command line.
 172                         break
 173                         ;;
 174         esac
 175         shift
 176 done
 177
 178 # Initialize the "buffer file" on file handle #3. This file will store all
 179 # output, stdout and stderr combined. The file is immediately unlinked so that
 180 # we can't leak stale files. Afterwards this script accesses the "buffer file"
 181 # by its file descriptor only.
 182 buffer_file=$(mktemp) \
 183         || ax_abort -l "Failed to create buffer file: \"$buffer_file\"!"
 184 ax_debug "buffer_file=\"$buffer_file\""
 185 exec 3>"$buffer_file" \
 186         || ax_abort -l "Failed to redirect FD #3 to buffer file!"
 187 if [[ -n "$proc_fd_works" ]]; then
 188         rm "$buffer_file" \
 189                 || ax_error -l "Failed to delete buffer file: \"$buffer_file\"!"
 190         buffer_file="/dev/fd/3"
 191 fi
 192
 193 if [[ $# -gt 0 ]]; then
 194         # Execute command and save output in buffer file.
 195         # Use a sub-shell to not pollute our name space!
 196         error_file=$(mktemp) \
 197                 || ax_abort -l "Failed to create error buffer file: \"$error_file\"!"
 198         ax_debug "error_file=\"$error_file\""
 199         exec 4>"$error_file" \
 200                 || ax_abort -l "Failed to redirect FD #4 to error file!"
 201         if [[ -n "$proc_fd_works" ]]; then
 202                 rm "$error_file" \
 203                         || ax_error -l "Failed to delete error buffer file: \"$error_file\"!"
 204                 error_file="/dev/fd/4"
 205         fi
 206
 207         job=$(basename "$1")
 208
 209         ax_debug "Running command \"$*\" ..."
 210         start_t=$EPOCHSECONDS
 211         exit_code=$(
 212                 "$@" 2>&1 1>&3 | tee "$error_file" >&3
 213                 echo "${PIPESTATUS[0]}"
 214         )
 215         end_t=$EPOCHSECONDS
 216 else
 217         # Read from stdin and save it to the buffer file.
 218         error_file="/dev/null"
 219         job="Job"
 220
 221         ax_debug "Reading from stdin ..."
 222         start_t=$EPOCHSECONDS
 223         while read -r line; do
 224                 echo "$line" >&3 \
 225                         || ax_abort -l "Failed to write to buffer file!"
 226         done
 227         end_t=$EPOCHSECONDS
 228         exit_code=0
 229 fi
 230
 231 ax_debug "exit_code=$exit_code"
 232
 233 declare -i count_all count_err
 234 count_all=$(wc -l <"$buffer_file" || ax_abort -l "Failed to count buffer file!")
 235 count_err=$(wc -l <"$error_file" || ax_abort -l "Failed to count error file!")
 236
 237 # Error or no error -- that's the question! An error is assumed when either the
 238 # exit code of the command was non-zero or there was output to stderr.
 239 # But when stderr_is_warning is set, messages on stderr result on a warning only!
 240 if [[ $exit_code -ne 0 ]]; then
 241         error_level=2
 242 elif [[ $count_err -gt 0 ]]; then
 243         [[ -n $stderr_is_warning ]] && error_level=1 || error_level=2
 244 else
 245         error_level=0
 246 fi
 247
 248 # Construct email subject ...
 249 [[ -z "$subject" ]] && subject="$host: $job report"
 250 if [[ "$error_level" -eq 0 ]]; then
 251         subject="$subject - success"
 252 elif [[ "$error_level" -eq 1 ]]; then
 253         subject="$subject - WARNING!"
 254 else
 255         subject="$subject - ERROR!"
 256 fi
 257
 258 ax_debug "from=\"$from\""
 259 ax_debug "to=\"$to\""
 260 ax_debug "subject=$subject"
 261
 262 if [[ -n "$DEBUG" ]]; then
 263         echo "--- stdout+stderr ---"
 264         cat "$buffer_file"
 265         echo "--- stderr ---"
 266         cat "$error_file"
 267         echo "---"
 268 fi
 269
 270 ax_debug "count_all=$count_all"
 271 ax_debug "count_err=$count_err"
 272 ax_debug "error_level=$error_level"
 273
 274 # No errors detected (exit code & stderr), and email should be sent on errors
 275 # only: so exit early!
 276 [[ "$error_level" -lt 2 && -n "$do_errors_only" ]] && exit $exit_code
 277
 278 # No error detected and no output at all: skip email, exit early:
 279 [[ "$error_level" -eq 0 && $count_all -eq 0 ]] && exit $exit_code
 280
 281 # Build the report mail.
 282 # Make sure to ignore all mail(1) configuration files, system wide /etc/mailrc
 283 # (by using the "-n" option) as well as ~/.mailrc (by setting the MAILRC
 284 # environment variable).
 285 export MAILRC=/dev/null
 286 (
 287         echo "$job report:"
 288         echo
 289         echo " - Host: $host"
 290         echo " - User: $(id -un)"
 291         echo " - Exit code: $exit_code"
 292         [[ -n "$time" ]] && printf " - Duration: %s\n" "$(time_t_to_duration $((end_t - start_t)) ' ')"
 293         echo
 294         if [[ $# -gt 0 ]]; then
 295                 # A command name is known (not stdin), show it!
 296                 echo "Command:"
 297                 echo "$@"
 298                 echo
 299         fi
 300         [[ -n "$time" ]] && printf "%s - %s:\n\n" "$(time_t_to_date "$start_t")" "$(time_t_to_date "$end_t")"
 301         if [[ $count_err -gt 0 ]]; then
 302                 # Prefix mail with all error messages.
 303                 echo "Error summary:"
 304                 echo "-----------------------------------------------------------------------------"
 305                 cat "$error_file" \
 306                         || ax_abort -l "Failed to dump error file!"
 307                 echo "-----------------------------------------------------------------------------"
 308                 echo
 309         fi
 310         if [[ $count_all -ne $count_err ]]; then
 311                 # Show full output when different to "error output" only.
 312                 cat "$buffer_file" \
 313                         || ax_abort -l "Failed to dump buffer file!"
 314         fi
 315 ) | mail -n -a "From: $from" -s "$subject" "$to" \
 316         || ax_abort -l "Failed to send email to \"$to\"!"
 317
 318 [[ -n "$dont_fail" ]] && exit 0 || exit $exit_code